Measurements and conclusion
Contents
We measured the Technics SU-G700M2 with the Prism dScope III. Noise at the mains was measured with and Tekbox LISN, common mode / differential mode splitter and the Picoscope 5000-series scope.
Measurements Technics SU-G700M2
Overall, the Technics measures very nicely. We see a noise floor of about -110dB, but the noise does climb up from about 50 kHz. Crosstalk is about 83dB which is good for an amplifier in this class.
We could not measure response with phase because the DSP throws a spanner in the works. The Prism can’t do anything with the feedback the Technics gives. Response can. We see some rolloff from 20 Hz to 5 Hz. 20 KHz is about -0.5dB. From 40 KHz the response shoots up by 4dB then shoots down (that must be a filter in the output).
Power is achieved spot-on. We measure 71 watts and 141 watts. If we measured at 1% it would be 82 watts and somewhere around 150 watts, we estimate.
Noise on the mains side is a bit high we find. We see it fluctuating anyway, which could have all kinds of reasons. But -59 dBu common mode noise we find a bit high. It certainly does not leak through into the signal path, but other equipment may suffer from it. A filter with a decent common mode choke is not a luxury in this case.